Method of forming a sound attenuating and gas passage tube construction



G. R.CROUSE METHOD OF FORMING A SOUND ATTENUATING Oct. '8, 1968 AND GASPASSAGE TUBE CONSTRUCTION Original Filed Sept. 14, 1964 2 Sheets-Sheet 1INVENTOR. 6L E/VA/ /2 64 0055 JWQW.

4 T TOAA/EK G. R. CROUSE METHOD OF FORMING A SOUND ATTENUATING Oct. 8,1968 AND GAS PASSAGE TUBE CONSTRUCTION Original Filed Sept. 14, 1964 v 2Sheets-Sheet 2 Eigi INVENTOR. 6L E/V/V A? 65 0035 A T TOANE United Stats. a e 073 .7 3,404,445 7 METHOD OF FORMING A SOUND AT- TENUATING ANDGAS PASSAGE TUBE CONSTRUCTION Glenn R. Crouse, Nuncia, Mich., assignorto Oldberg Manufacturing Company, Grand Haven, Mich., a corporation ofMichigan I Original application Sept. 14, 1964, Ser. No. 396,247, nowPatent No. 3,276,540, dated Oct. 4, 1966. Divided and this applicationMay 23, 1966, Ser. No. 552,059

9 Claims. (Cl. 29-157) This is a division of my copending applicationSer. No. 396,247 filed Sept. 14, 1964, now Patent No. 3,276,- 540.

This invention relates to the attenuation of sound waves in gas streamsand particularly to apparatus for attenuating sound waves in exhaust gasstreams from internal combustion engines and to a method of producingthe apparatus.

It has been conventional practice in connection with automotive vehiclespowered by internal combustion engines to convey the, exhaust gasesthrough a sound attenuating muffler or silencer of substantial size toattenuate sound waves in the exhaust gas streams. A recent trend inautomotive design is to lower the vehicles and such design necessitatesadditional struts and stress resisting frame members and such framemembers render difiicult the installation and use of conventionalmuffler constructions.

Recent developments have been made in the use of an exhaust conduitconstruction embodying a plurality of connected sound attenuating unitswherein the outer shells or members of the attenuating units areconnected together in end-to-end relation to form a combined exhaustpipe and sound attenuating means.

It is found that in the use of constructions of this characterconsiderable so-called shell noise is developed by reason of thecomparatively thin single outer shells of the sound attenuatingconstructions connected to provide the exhaust gas conduit.Constructions of such character are desirable in that they provide'for asubstantially unobstructed gas passage means with a plurality of soundattenuating constructions disposed in close relation or spaced inend-to-end relation, and by reason of the length of the assembly ofattenuating units, objectionable sound waves in the gas stream areattenuated but the single layer outer shells are readily responsive tosound vibrations causing shell noise.

An object of the invention resides in a method of forming a soundattenuating unit or construction having a central gas passage means, aplurality of sound attenuating chambers adjacent and surrounding the gaspassage means and an outer, wall or layer embracing the soundattenuating meansjwherein an inter-mediate shell of thesound'attenuating, means is distorted by lengthwise pressure duringprocessing 'into close or snug engagement with the gas passage means andthe outer shell or layer whereby the components are held in assembledrelation by the distorted regions or portions of the intermediate shellproviding annular spaces between the intermediate and outer shells toreduce shell noise.

Another object of the invention resides in a method of fabricating adual shell casing of a sound attenuating construction wherein one of theshells is contracted in a lengthwise direction to effect a transversedistortion of lengthwise spaced regions thereof into snug engagementwith the other shell to secure the shells in assembled relation andprovide a plurality of closed annular chambers between the shells.

Further objects and advantages are within the scope of this inventionsuch as relate to the arrangement, opera- 7 3,404,445 Patented. Oct. 8,1968 tion and "function of the related elements of the structure, tovarious details of construction and to combinations of 'parts, elementsper se, and to economies of'm'anufacture and numerous other features aswill be apparent from a consideration of the specification and drawingof a form of the invention, which may be preferred, in which:

FIGURE 1 is a phantom or a schematic view of the frame or chassisconstruction of an automotive vehicle and internal combustion engineillustrating a form of tuned exhaust pipe assembly or sound attenuatingsystem of the invention;

FIGURE 2 is an elevation-a1 view of the sound attenuating or tunedexhaust pipe illustrating one arrangement of sound attenuating units inthe exhaust system for use with an internal combustion engine;

FIGURE 3 is a longitudinal sectional view illustrating one of the soundattenuating units of the exhaust system;

FIGURE 4 is a transverse sectional view taken substantially on the line4-4 of FIGURE 3;

FIGURE 5 is a longitudinal sectional view illustrating a step in themethod of forming one of the sound attenuating units;

FIGURE 6 is a sectional view similar to FIGURE 5 illustrating a furtherstep in the method of forming the sound attenuating unit; I

FIGURE 7 is a longitudinal sectional view showing a plurality ofattenuating units in connected relation forming a combined gas passageand sound attenuating construction;

FIGURE 8 is an elevational view of the construction shown in FIGURE 7,and

FIGURE 9 is a transverse sectional view illustrating the method ofjoining adjacent attenuating units.

The longitudinally aligned assembly of sound attenuating units andcoupling tubes in end-to-end relation, provides a combined exhaust pipeand sound attenuating construction or tuned exhaust pipe havingparticular utility as an exhaust system for internal combustion enginesin automotive vehicle constructions, the arrangement providing aneffective instrumentality for attenuation of sound waves of varyinglengths entrained in the exhaust gas stream and for reducing shellnoise, the tubular assembly being configurated to avoid interferencewith other structural components of the vehicle. I

Referring to the drawings in detail and initially to FIG- URE 1, thereis illustrated in phantom or schematic form, a vehicle frame or chassis10 embodying longitudinally extending side frame members 12 andtransversely disposed struts or reinforcing members 14. The frontalregion of the frame 10 supports an internal combustion engine 16 ofconventional V-type construction having two banks 17 of cylindersequipped with exhaust manifolds 18, an exhaust pipe or gas conveyingtube 20 is fashioned with branches 21 and 22 connected with therespective manifolds 18 of the engine.

In the arrangement shown in FIGURE 1, the exhaust gas streams from bothbanks of cylinders 17 are converged into a single tubular means which isconnected with the tuned exhaust pipe system of the invention, thelatter being preferably of a character for conveying the exhaust gasesfor discharge at the rear of the vehicle. While FIGURE 1 is illustrativeof an arrangement employing a single tubular exhaust conveying systemfor the exhaust from both banks of cylinders, it is to be understoodthat a separate exhaust conveying and sound attenuating means or systemmay be employed for the exhaust stream from each bank of cylinders. I

The exhaust conveying and sound attenuating arrangement of the inventioncomprises a plurality of gas-conveying and sound attenuating units, eachcontained within an outer shell or enclosure and the outer shells orenclosures welded or otherwise coupled together in end-to-end c'oupledtogether by a tubular coupling 32, units 26a and 26b directly joinedtogether, and the units 26b and 26c coupled by a tubular component 34 ofa configuration to provide clearance or jounce space for an axle of thevehicle. The units 26 through 26c are of substantially the sameconstruction although they may be fashioned of varying lengths and maybe spaced lengthwise other than the arrangement illustrated in FIGURES 1and 2 in order to attenuate a particular range of sound waves dependingupon the degree or efiiciency of sound attenuation desired.

One of the attenuating units 26 is illustrated in FIG- URES 3 and 4, andsteps in the method of assembling the components of the attenuatingunits are illustrated in FIGURES 5 and 6. With particular reference toFIGURE 3 each attenuating unit or construction is inclusive of a centraltubular member 40 which provides a gas passage means or tube, the wallof the tube 40 being provided with a comparatively large number of smallopenings 42. Surrounding the gas passage tube 40 and spaced therefrom isa second tubular member or shell 46 which is preferably of circularcross section and concentric with the tube 40 as shown in FIGURE 4.

The shell 46 is distorted or configurated at lengthwise spaced regionsduring forming operations providing transverse partitions 48 whichengage the peripheral surface of the gas passage tube 40 to secure thetube 40 and shell 46 in assembled relation. In the attenuating unit ofthe invention, an outer shell or tube 50 is telescoped over the adjacentshell 46 and is secured in fixed relation with the shell 46 by raisedridges 52 formed of the metal of the shell 46 during distortion of thespaced regions of the shell to form the partitions 48.

Each of the attenuating units, as shown in FIGURE 3, comprises an outertubular layer or shell 50 and an adjacent inner shell 46, the shell 46being of slightly lesser diameter than the shell 50 providing annularspaces or chambers 54 of a length equal to the'distance between adjacentridges 52, the annular chambers 54 providing closed air spacesfunctioning :as cushioning means for reducing shell noise or noisescaused by vibration of the shell 46 set up by sound waves of the movingexhaust gases.

The friction set up in the method of assembly between the distortedportions forming the partitions 48 and the gas passage tube 40 andbetween the outwardly distorted ridges 52 and the outer tube or shell 50securely retains or holds these components of each attenuating unit inproper relation without extraneous fastening means. The annular spaces53 between the gas passage tube 40 and the shell 46 and definedlengthwise by the partitions 48 provide sound attenuating chambersacoustically coupled with the interior of the gas passage tube 40 by theopenings 42.

FIGURES 5 and 6 illustrate steps in the method of assembling the gaspassage tube 40, the shell or tubular member 46 and the outer shell orclosure 50. The shell 46 is initially of cylindrical tubularconfiguration, and in a preforrning operation at spaced regions alongthe tube, the metal is spun or distorted inwardly to form the peripheralrecesses or grooves 55. The inner diameter of each of the inwardlyextending ridges provided by a recess 55 is slightly greater than thediameter of the outer surface of the gas passage tube 40, the latterbeing telescoped interiorlyof the shell 46 in the position shown in FIG-URE 5, and the outer tube or shell 50 telescoped over the shell 46.

' Disposed at one end of this assembly is a base block or bolster 60fashioned with a first circular groove 62 to accommodate the end of thegas passage tube 40, a circular ledge 64 against which abuts the end ofthe shell 46,

and a second circular groove 66 which receives anend of the outer shellor tube 50. Disposed at the opposite end of the assembly is a movableram 70 of a conventional press (not shown) fashioned with a circulargroove 72 which receives the opposite end of the shell 46 during closingor operative movement of the pres'sjram.

As will be apparent from FIGURE'S, the shell 46, priorto the distortionoperation to form the partitions 48 shown in FIGURES 3 and 6, extends asubstantial distance beyond the adjacent ends of the gas passage tube 40and the tube or outer shell 50. l p

The press ram 70 is fashioned with a circular recess accommodating anannularmember 74 of rubber or other nonmetallic material which isaligned with the gas passage tube 40. The ram 70 is provided with aledge forming a seat for a second annular member 76 of rubber or othernonmetallic material aligned with the outer shell or closure 50.

With the components 40, 46 and 50 predisposed in the relative" positionsshown in FIGURE 5, the ram 70 is moved toward the components to theposition shown in FIGURE 6. During movement of the ram to this position,the ram exerts lengthwise crushing or compressive forces against theshell 46, lengthwise thereof, which forces distort the regions of theshall defining the grooves 55 to bend or distort the metal to form thedouble layer partitions 48. By reason of the crushing stresses exertedon the tub 46, outwardly extending circular beads or ridges 52 areformed which frictionally and snugly engage the outer shell or closure50 in the manner shown in FIG- URES 6 and 9.

Thus a complete attenuating unit with the outer shell is formed by themethod step shown in FIGURE 6. The annular members 76 and 74 carried bythe ram 70 provide resilient cushions to prevent damage to or distortionof the gas passage tube and the outer shell or tube 50 during the stepof distorting portions of the shell 46 in assembling the components.

As particularly shown in FIGURE 3, the left-hand end of the outer shellor tube 50 extends beyond the adjacent ends of the shell 46 and gaspassage tube 40 while at the other and of the assembly, the shell 46 andthe gas passage tube 40 extend beyond the adjacent end of the outershell 50. FIGURE 9 illustrates the relative positions of adjacentattenuating units with the outer shells 50 aligned and welded togetherto form a continuous tubular construction.

In assembly, the ends of outer shells 50 are abutted and welded as at 80throughout the circumference of the butting regions of the walls to forma continuous impervious tube. It will be noted from FIGURE 9 that theends of adjacent gas passage tubes 40 and adjacent ends of the innershells 46 are respectively aligned but are slightly spaced as at 94 tofacilitate the welding 80 without interference between adjacent ends ofthe members 40 and 46. j

FIGURES 7 and 8 illustrate a modified assembly of several soundattenuating units with the outer shells joined to provide a singleexhaust pipe or gas passage tube. As shown in FIGURES 7 and 8, twoattenuating units 26a and 26b of substantially identical construction,are dis posed in abutting relation and the outer shells 50 weldedtogether at the weld line 80. The forward end of the unit 2611 may bewelded as at 81 to a coupling tube such as the tube 32 shown inFIGURE 1. e Y

A third unit 260 of the arrangement shown in FIG- URES 7 and 8 is spacedfrom the other units by a length of tubing 84 of the same diameter asthe outer shells 50, the ends of the tube 84 being welded to theadjacent ends of the attenuating units as at 86 and 88. The thirdattenuating unit may be Welded to a tailpipe member 90 as at the weldline 92. The outer shells 50 of the attenuating units with theconnecting tube 84 provide a continuous imperforate exhaust gas passagetube which may be of a shape similar to that shown in FIGURE 1 forconveying exhaust gases from the engine exhaust manifold for dischargeinto the air through the tailpipe 90. 7 It is to be understood that theintermediate or coupling tube 84 may be bent to a desired shape such asthe tube 34 shown in FIGURE 2 to provide clearance space for a componentofthe vehicle frame construction.

The assemblage of sound attenuating units having their outershells'welded together or joined by coupling tubes in the mannerdescribed provides a comparatively long imperforate tubular means orpipe for conveying exhaust gases and enclosing the attenuating units forattenuating sound waves over abroad range of valve lengths to attainimproved sound attenuation and reduce shell noise.

Through this arrangement sound waves of short length and high pitch arereadily attenuated as well as longer waves of low pitch by reason of thesubstantial distance traversed by the exhaust gases in moving throughsuccessive sound attenuating units.

It is to be understood that the relative lengthwise arrangement of thesound attenuating units may be varied by interposing a tubular couplingmember, such as members 32, 34 or 84 between each pair of soundattenuating units, and such tubular members or couplings may be ofvarying lengths to secure desired attenuation of sound waves.

It is apparent that, within the scope of the invention, modificationsand different arrangements may be made other than as herein disclosed,and the present disclosure is illustrative merely, the inventioncomprehending all variations thereof.

' Iclaim:

1. The method of forming a multiple tube assembly including the steps ofdistorting metal of the wall of a first tube inwardly at lengthwisespaced regions, telescoping the first tube between second and thirdtubes of diameters whereby the first tube is spaced from the second andthird tubes, and impressing pressure lengthwise on the first tube toforce'the metal at the lengthwise spaced regions into engagement withthe second tube and the third tube for securing the tubes in assembledrelation with annular regions between the first and second tubes andbetween the first and third tubes, the distorted metal providingpartitions subdividing the annular spaces into lengthwise arrangedindividual chambers.

2. The method of forming a multiple tube assembly including the steps ofdistorting metal of the wall of a first tube at lengthwise spacedregions to form circular grooves therein, telescoping the first tubehaving the circular grooves between second and third tubes of diameterswhereby the first tube is concentric with and spaced from the second andthird tubes, and impressing pressure lengthwise on the first tube toconcomitantly force one region of the metal defining the groovesinwardly into engagement with the second tube and another region of themetal outwardly into engagement with the third tube for securing thetubes in assembled relation with annular regions between the first andsecond tubes and between the first and third tubes and whereby thedistorted metal forms partitions subdividing the annular regions intolengthwise arranged individual chambers.

3. The method of forming a telescoped tube assembly including the stepsof distorting metal of the wall of a first tube to form longitudinallyspaced inwardly extending circular grooves, disposing a second tube oflesser diameter having a perforated wall region within the first tubewith the tubes in concentric relation, telescoping an imperforate walledthird tube over the first tube and in concentric relation with andspaced laterally from the first tube to provideannular regions betweenthe first and second tube and between the first and third tubes, andimpressing pressure lengthwise on the first tube to concomitantly forcea portion of the metal adjacent the grooves inwardly into engagementwith the perforated tube and another portion of the metal outwardly intoengagement with the third tube for securing the tubes in assembledrelation and thereby. forming lengthwise arranged annular chambersbetween the first tube and the second and third tubes.

4. The method of forming telescoped tube constructions and connectingthe tube constructions including the steps of distorting metal of thewall of a first tube to form longitudinally spaced, inwardly extendedcircular grooves, disposing a second tube of lesser diameter having aperforated wall region within the first tube with the tubes inconcentric relation, telescoping a third tube having imperforate wallsover the first tube and in concentric relation with and spaced from thefirst tube to providing an annular region between the first and secondtubes, impressing pressure lengthwise on the perforated tube toconcomitantly force a portion of the metal adjacent the grooves inwardlyinto engagement with the perforated tube and another portion of themetal outwardly into engagement with the third tube for securing thetubes in assembled relation and forming lengthwise arranged annularspaces between the first tube and the second and third tubes and theannular spaces subdivided into chambers by the distorted metal of thefirst tube, said first and second tubes being of lesser length than thethird tube, disposing two of the telescoped tube constructions with thethird tubes of each in end-to-end relation and connecting the thirdtubes to form a continuous imperforate pipe.

5. The method of forming a gas conveying duct enclosing tubular soundattenuating constructions including the steps of distorting metal of thewall of a first tube to form longitudinally spaced inwardly extendingcircular grooves, disposing a second tube of lesser diameter having aperforated wall region within the first tube with the tubes inconcentric relation forming an annular region between the first andsecond tube, telescoping a third tube having imperforate walls over thefirst tube and in concentric relation with and spaced from the firsttube to provide an annular region between the first and third tube,impressing pressure lengthwise on the perforated tube to concomitantlyforce the metal adjacent the grooves into engagement with the second andthird tubes for securing the tubes in assembled relation and subdividingthe annular spaces between the first tube and the second and third tubesby the distorted metal of the first tube into lengthwise arrangedindividual chambers, said first and second tube constituting a soundattenuating construction, disposing two of the sound attenuatingconstructions with the third tubes in abutting end-to-end relation, andwelding the abutting regions to form a continuous imperforate gasconveying duct.

6. The method of forming and joining telescoped tube assembliesincluding the steps of distorting metal of the wall of a first tube toform longitudinally spaced inwardly extending circular grooves,disposing a second tube of lesser diameter having a perforated wallregion within the first tube with the tubes in concentric spacedrelation, telescoping a third tube having imperforate walls over thefirst tube and in concentric relation with and spaced from the firsttube, impressing pressure lengthwise on the first tube to concomitantlyforce the metal adjacent the grooves into engagement with the first tubeand with the third tube for securing the tubes in assembled relation andforming lengthwise arranged annular spaces between the first tube andthe second and third tubes and separated by the distorted metal of thefirst tube into individual chambers, said first and second tubes inassembly being of lesser length than the third tube, disposing two ofthe telescoped tube assemblies with the third tubes of each in abuttingend-to-end relation, and welding the abutting regions to form acontinuous imperforate wall with the adjacent end regions of the firstand second tubes of the telescoped tube assemblies in spaced relation.

7. A method of forming a sound attenuating and gas passage tubeconstruction for use with the exhaust gas stream of an internalcombustion engine of an automotive vehicle including the'steps ofpre-assembling an inner perforated-gas passage tube within and spacedtransverse- 1y from an intermediate tube of larger diameter, saidintermediate tube having annular grooves formed therein atspacedregions, telescoping an outer tube, of a diameter larger than theintermediate tube and having an imperforate'wall over the intermediatetube in concentric relation Withwthfi intermediate tube, exertingpressure lengthwise on the intermediate tubeto distort lengthwise spacedregions'of the intermediate tube laterally into engagement with theinner gas passage tube and into engagement with the outer tube to securethe tubes in spaced relation. r

8. A method of forming a sound attenuating and gas passage tubeconstruction for use with the exhaust gas stream of an internalcombustion engine of an automotive vehicleincluding the steps of forminga telescope tubular assembly by pre-assembling an inner perforated gaspassage tube within and spaced transversely from an intermediate tube oflarger diameter, said intermediate tube having annular grooves formedtherein at spaced regions, telescoping an outer tube of a diameterlarger than the intermediate tube and having an imperforate wall overthe intermediate tube in concentric relation with the intermediate tube,exerting pressure lengthwise of the intermediate tube to distortlengthwise spaced re gions of the intermediate tube laterally intoengagement with the inner gas passage tube and into engagement with theouter tube to secure the tubes in spaced relation, abutting the adjacentends of outer tubes of two of said telescoped assemblies, and weldingthe abutting regions of the outer tubes together circumferentially toform a gas tight seal.

9. A method of forming a sound attenuating and gas passage tubeconstruction for use with the exhaust gas stream of an internalcombustion engine of an automotive vehicle including the steps offorming a telescoped tube unit by pre-assembling aninner perforated gaspassage tube within and spaced transversely from an intermediate tube oflarger diameter, said intermediate tube having annular grooves formedtherein at spaced regions, telescoping an outer tube of a diameterlarger than the intermediate tube and having an imperforate wall overthe intermediate tube in concentric but in spaced transverse relationwith the intermediate tube, exerting pressure lengthwise of theintermediate tube to distort lengthwise spaced regions of theintermediate tube laterally into engagement with the inner gas passagetube and into engagement with the outer tube to secure the tubes inspaced relation, abutting the adjacent ends of outer tubes of two ofsaid telescoped tube units, welding the abutting regions of the outertubes together circumferentially to form a gas tight seal, disposing .anend of a plain tube in engagew ment with an end of one of saidtelescoped tube units, and welding the engaging regions of the outertube of the adjacent telescoped tube unit to the end of the plain tubeto form a sealed joint.

References Cited UNITED STATES PATENTS 1,878,424 9/1932 Oldberg 181-482,047,442 7/1936 Starkweather et al. 181-48 2,148,948 2/1939 Kingsley18148 2,683,928 7/1954 Carson 29523 3,204,164 8/1965 Burke et a1.

3,219,142 11/1965 Deremer.

3,242,558 3/1966 Selig 29-520 X CHARLIE T. MOON, Primary Examiner.

1. THE METHOD OF FORMING A MULTIPLE TUBE ASSEMBLY INCLUDING THE STEPS OFDISTORTING METAL OF THE WALL OF A FIRST TUBE INWARDLY AT LENGTHWISESPACED REGIONS, TELESCOPING THE FIRST TUBE BETWEEN SECOND AND THIRDTUBES OF DIAMETERS WHEREBY THE FIRST TUBE IS SPACED FROM THE SECOND ANDTHIRD TUBES, AND IMPRESSING PRESSURE LENGTHWISE ON THE FIRST TUBE TOFORCE THE METAL AT THE LENGTHWISE SPACED REGIONS INTO ENGAGEMENT WITHTHE SECOND TUBE AND THE THIRD